The invention relates to track fittings for use in anchoring loads to the floor of aircraft. Typically, an aircraft floor includes a plurality of parallel, longitudinally slotted, channel-like tracks arranged flush with the floor down the length of the interior. The tracks have alternate wide and narrow openings which are commonly spaced at a one inch pitch so that fittings for anchoring seats or cargo can be located at any desired multiple inch increment along the length of the track. The fittings and associated track must typically be able to support 4000 pound vertical and 3600 pound horizontal loads. One commercially available fitting which meets these requirements comprises a housing which carries a vertically movable shear pin and an operating handle therefor at its forward end and a pair of threaded, headed retaining studs on one inch centers at its rearward end. The headed studs are adapted to be slid under retaining lips in the track and the shear pin is then lowered into the wider openings in the track to prevent forward movement. A transverse aperture is located in the housing midway between the studs for attaching a load to the fitting. Since the fittings being discussed are usually, when used on a seat, only used on the rear legs of the seat, the forces acting on the fittings in a crash situation will typically be forward and upward. These forces are resisted by the forward edge of the shear pin and the two studs with most of the vertical force being resisted by the rear stud as the fitting tends to pivot about the forward edge of the forwardly mounted shear pin. The forward stud can absorb very little of the load until the track and rear stud start to deflect. As the fitting starts to fail under load, the rear stud typically pulls out of the track, causing all of the vertical loading to be transferred to the front stud which then also pulls out.
Although the aforementioned fittings are sufficiently strong for use on each of the two legs of a double seat, they do not have sufficient strength to support a triple seat where the triple seat must be carried by the same two tracks as a double seat with one seat position cantilevered into the aisle. Increased density seating is being strongly considered as an alternative to the tremendous expense associated with the purchase of new aircraft and as a means to decrease the amount of fuel consumed per passenger mile. In one widebody aircraft presently utilizing an eight abreast seating configuration consisting of four double seats, capacity can be increased considerably by using a triple-quad-double configuration to provide nine abreast seating. However, the additional loading provided by the substitution of a two leg triple seat for a two leg double or a three leg quad seat for a pair of two leg doubles would necessitate that the front and rear legs of each seat be spaced apart by about 22 inches rather than the conventional 18 inches. When one considers that the seats are normally spaced at a pitch of only 32-36 inches or less, it is obvious that the small amount of aisle space in front of the seats could not comfortably accommodate rear seat legs which extend four inches further back into the aisle space than before. Alternatively, the seat track in the aircraft could be replaced with a much heavier track but the cost would be very high and the additional weight of the heavier track would increase operating costs and decrease the load capacity.